Issues to think about - Message board design

[Sul]

Hi

I need to design and code from scratch (because I want to - it'll be educational) a little forum - mini forum really. Basically it'll be like a feedback board, where users enter comments, they are logged and displayed on a page in one thread (maybe more, not decided yet).

What kind of security and coding issues do I need to consider?

[rgermain]

One thing off hand I can think of is making sure the people can't enter malicous code into the area where they will be able to enter their comments.